Air conditioning system



Jan. 6, 194-2. 3, CRAWFORD 7 2,269,053

AIR CONDITIONING SYSTEM Filed Oct. 17, 1939 CD/VD/T/ONED ABE/1 ditioningof enclosures by heat.

Patented Jan. 6, 1942 UNITED STATES PATENT OFFICE.

2,269,053 AIR CONDITIONING SYSTEM Robert B. r. Crawford, Athens, Ga.

Application October 17, 1939, Serial No. 299,883

12 Claims.

This invention relates to a system for the conthe adjustment of the heatand humidity content to a desired level or range and is particularlydirected'to' a system involving the combined use of mechanicalrefrigeration and absorption. 7

A principal object of the invention is to provide a system for theconditioning of enclosures wherein a compression-evaporationrefrigeration system is used for the removal of sensible heat 0 and anabsorbing medium, for example, a hygroscopic liquid is used for theremoval of latent A further object of the invention is the'provision ofa combined system wherein the heat of compression and condensation ofthe refrigerant medium, such as Freon, is utilized for the concentrationof the hygroscopic solution.

A further object of the invention is the provi-" sion of a combinedsystem whereby the evaporative cooling eifect of atmospheric air is.utilized for the cooling of the liquefied refrigerant medium or thehygroscopic absorption medium or both.

Further objects and advantages will be ap-. parent from thefollowingdescription of an illustrative embodiment of the inventionwithparticular reference to the accompany drawing.

The system illustrated comprisesa refrigerant n compressor 1, aconcentrator 2, cooling tower 3, an expansion water cooler l, and adehumidifying chamber 5, together with suitable heat exchange andcontrol devices. The system will be described with reference to the useof Freon as a refrigerant medium and calcium 215 chloride brine as ahygroscopic or dehumidifying agent.

The Freon compoun compressed in compress- .or I to 265 pounds per squareinch is conducted through extended surface coils ID of concentra tor 2.Here it gives up its heat of compression and condensation todilutedcalcium chloride brine flowing over the coils from sprays ll, and

is condensed at say 155 F.

The heated brine is concentrated by the-action of a current of air blownupwards over coils II] by blower l2. Increased heat economy may beobtained by the use of a heat transfer medium circulated by pump goingair at H and, the incoming air at Freon and the hot fconcentrated brinepass through a heat exchanger .16 wherein they are cooled by the brinepassing to the concentrator.

an evaporative l3 between the heated out I5. Thai" 38. through exchangerinreturning to cooler 4; the-amount of water passing to; the exchangerThe Freon 1 and the concentrated brine arefur ther cooled'by heatexchange with a stream of er 3, being supplied to the tower at pointswhere the equilibrium wet bulb temperature is approximately the same asthe temperature of the Freon and brine, respectively. The brine passesserially through coils 20, 22, 24, 26 and 28, and the Freon throughalternating coils 2|, 23, 25 and 21.

The Freon and brine are cooled in the tower by the evaporative coolingeffect of a current of air blown upwards through the tower by blower I!)where it' evaporates and cools waterfrom heat exchangers IT, IS to atemperature approaching the wet bulb temperature of the available air,say E. if the atmospheric air has a dry bulb-temperature of 100 F. and adew point of-'73- F.

The Freon coming from coil 21 at about F. is expanded through valve 4'into water cooler 4, cooling the water'therein to about 60 F., and thegaseous Freon at about 55 F. is returned to compressor l. g

Cooled concentrated brine at about 87 F. is sprayed throughsprays 29 indehumidifier 5 over extended surface coils 30 at about 85 F. from thesump cooling tower 3 is circulated by means of pump This water isthenreturned through heat exchangers Hi to sprays 33 at the top ofevaporative cooling tower 3. .The water evaporated in cooling tower 3 isreplenished through float controlled valve 51. The make-up water ispreferably added to the tower, for example, through sprays 33a, atapoint where the equilibrium wet bulb temperature is approximately thesame as the temperature of the available watersupply.

Atmospheric air at, say F. dry bulb, 80 F. wet bulb, and 73 F. dew pointis drawn through dehumidifier 5 by blower 34 and is cooled anddehuniidifled herein to 92 F. dry bulb, 66 F. wetbfulb and 50 F. dewpoint. This air is then further cooled by heat exchangewith cool waterin heat exchanger 35 to a dry bulb temperature of, for example, 80 F.and is led into the condi- 3I of evaporating 'tionedarea throughregisters 36.- 1

to radiators 31 in the conditioned area... air in the area beingcirculated over the radiators by fans Water from the radiators iscirculated being controlled by valve 39 actuated by thermothrough whichwatertothe brine when the temperature of the enment.

stallation.

drawn out by means of a "the dissipation of the heat ofdehumidific'ation stat 40 in the air duct leading to the conditionedarea. 1

The temperature in the conditioned area is controlled by thermostatwhich actuates valve 42 supplying steam to tempering coil .43 and alsogoverns motor 44 which drives compressor I.

The humidity in the conditioned area is controlled by humidostat 45which actuates valves 46 governing the amount of heating surface inconcentrator 2 by varying the amount of coil i through which thecompressed refrigerant is caused to flow, thus regulating theconcentration of the brine supplied to dehumidifier 5. In peri-' ods ofhigh humidity and low dry bulb temperature, humidostat 45 may be alsoutilized to actuate the supply of additional heat to concentrator 2 froman outside source. not shown.

The temperature of the air drawn into dehumidifier 5 is prevented fromfalling to a point low enough to cause solidification of the brine inthe humidifier by means of steam tempering coil 41 controlled by valve41a actuated by thermostat 48. Thermostat 48 may also actuate floatvalve 49 to permit the addition of water tering air falls below ,apredetermined limit. Valve 49 may be'interconnected with valve 41athrough a potentiometer circuit, which may be' precalibrated to a veryclose degree of adjust- In general, it is desirable that the heat ofcompression and condensation of the refrigerant cycle should balance theheat required for concentrating the hygroscopic liquid under averageconditions prevaillng ,in the region of the in- Instead of the air draftconcentrator shown in the drawing, the concentrator may beadvantageously operated as a reduced pressure. evaporator, the vaporsfrom the concentrator being water ejector utilizing water from thedehumidifier cooling circuit discharged by pump32. This water is sprayedupt wardly into the evaporative cooling tower, in accordance with themethod described in my application SerialNo. 215,280; filed June' 22,1938,

now Patent No. 2,200,442, issued May-l4, 1940, .the water being suppliedto the tower at a point where the equilibrium temperature isapproximately the same as the (temperature of the water coils and 26. Jg

It will be seen that the ;invention provides a flexible system ofcombined eompression-expan- 56 \coming fromthe-elector, forexample-between erant under evaporative conditions for concentration ofthe hygroscopic liquid and condensation of the refrigerant, and meansfor bringing the concentrated hydroscopic liquid into heat exchangerelationship with water while subjectingthe, water to the evaporativecooling effect of a current of air.

2. An air conditioning system comprising a compression-expansionrefrigerant cycle includfrom the conditioned area to the refrigerant, a

hygroscopic liquid cycle including means for ing the water-to theevaporative cooling effect ofa current of air flowing counter-current tosaid hygroscopic'liquid and.said water. I

3. ,An air conditioning system comprising a compression-expansionrefrigerant cycle including heat transfer means for the transfer of heatfrom the conditioned area tothe refrigerant, a hygroscopic liquid cycleincluding means for contacting air supplied to the conditioned area withthe hygroscopic liquid 'for removal of moisture from the air, heatexchange means whereby the hygroscopic liquid is brought into heatexchange relationship with the compressed refrigerant under evaporativeconditions for concentration of the hy r scopic liquid and condensationof the refrigerant, and means for bringing the condensed refrigerantinto heat exchange relationship with water while subjecting the water tothe evaporative cooling effect ofa current of air.

4. An air conditioning vsystem comprising a compression-expansionrefrigerant cycle including heat transfer means for thetransfer of heatfrom the conditioned area to the refrigerant, a

hygroscopic liquidcycle including means for contacting air supplied tothe conditioned "area;

with the hygroscopic liquid for removal of moisture from the air, heatthe hygroscopic liquid erant under "evaporative conditions for"concentration ofthe hy rosco ic liquid and condensation of therefrigerant,

sion cooling and hygroscopic solution dehumidithe eondensed' refrigerantinto, heat exchange 'flcation in which the heat of compression and areeflected by the evaporative cooling effect of atmospheric air on a watercooling circuit opcrating under truly counter-current heat ex-,

change principles throughout the system.

I claim: e 1. An air conditioning system comprising acompression-expansion refrigerant. cycle .including heat transfer meansfor the transfer of heat from the conditigned area to the refrigerant, a

hygroscopic liquid cycle including means for 70 g 4 I e of tirehygroscopic liquid and condensation of "contacting air supplied to theconditioned area 4 with the hygroscopic liquid for removal of moist.

change relationship'with the compressed refrigk" acompression expansionrefrigeran't'cycle includtacting air relationship with water whilesubjecting the rent of-air flowing densed refrigerant 5.:An a

counter-current to said conand said water. 7 conditioning systemcomprising a ing heat transfermeansfor the transfer of heat from theconditioned area to the refrigerant, a hygroscopic liquid cycleincluding means for consupplied to the conditioned area with -thehygroso'cpicliquid: for removalof moisture from the air, heat exchangemeans whereby the hygroscopic liquidis brought intoheat exchangerelationship withthe compressed refrigerant under evaporative[conditions for concentration the refrigerant, and meansfor bringingthecons water-while subjecting the water to the evapoing heat transfermeans for the transfer of heat brought into heat exexchange meanswhereby is brought into heat ex-' change relationship with thecompressed refrigand means for bringing cult, means for passing acurrent'of air in direct contact with the hygroscopic liquid passingoverrative cooling effect of a current of air flowing coimter-current tosaid condensed refrigerant, said hygroscopic liquid and said water. 6;In an air conditioning system wherein sensible heat is removed by theexpansion of a liquefled refrigerant and moistureis removed by ahygroscopic liquid, the steps comprising condensing the refrigerant byheat exchange with the'hygroscopic liquid while maintaining thehygroscopic liquid under conditions of free evaporation, and thereafterremoving the heat from the h grocooling effect of a stream of water incontact witha current of air.

8. An air conditioning system comprising in combination a refrigerantcircuit comprising a compressor, extended surface condensing coils,

extended surface cooling coils-, an expansion chamber in heat exchangerelationship with the conditioned area and means for passing arefrigerant medium serially through csaid corn pressor, condensingcoils, cooling coils and ex-.

pansion' chamber; a, dehumidifyingcircuit including extended surfacecooling coils, anextended contact surface adapted for directlycontacting air with a hygroscopic liquid, and means I for passing ahygroscopic liquid serially through said coolin coils, over saidextended surface and over the ex ended surface condensing coils of therefrigerant circuit; means for passing stream of water under conditionsof free e aporation over the extended surface cooling coils of bdth therefrigerant circuit and the dehumidifyin'g circuit; means for passing acurrent of air in (ii-- ect contact with the hygroscopicliquld passingover said extended surface, and means for conducting said current of.air into said conditionedarea. 1

' 9; An air conditioning system comprising in combination a refrigerantcircuit comprising-a compressorQextendd surface condensing coils,extended surface cooling coils, an expansion chamber in heat exchangerelationship with the conditioned area and means for passing-a re-.

frige'rant medium serially through said -com-' pressor, condensingcoils, cooling coils andiexpan'sion chamber: a dehumidifying circuitin-,'

eluding extended surface cooling coils, an extended contact surfaceadapted for directly con tacting airfwith a hygroscopic liquid,-andmeans for passing a'hygroscopic liquid serially through said extendedsurface, and means for conducting said current of ,air into saidconditioned space.

10; An air conditioning systemcomprising a compression-expansionrefrigerant cycle including heat transfer mean 'for the transfer of heatfrom the conditioned rea to therefrigerant, a hygroscopic liquid cycleincluding means for-contacting =air supplied to the conditioned areawith the hygroscopic liquid for removal of moisture from the air, heatexchange means whereby the hygroscopic liquid is brought into heatexchange relationship with the compressed refrigerant, under evaporativeconditions 'for concentration of the hygroscopicli'qui d condensation ofthe refrigerant,- an evapora ve cooling tower including a pluralityofextended surface coils, means for causing a stream of water to flowdownward ly over saidscoils, means for flowing a stream of air upwardlyover said coils, means forpassing condensed refrigerantv through aportion of said coils, and means" for passing concentrated brine throughanother portion of said coils.

11. An air conditioning system comprising a compression-expansionrefrigerant cycle including heat transfer means for the transfer of heatfrom the conditioned area to the refrigerant, a

- hygroscopic liquid cycle including means for coni tacting air suppliedto; the conditioned area with the hygroscopic liquid for removal ofmoisture from the air, heat exchange means whereby the hygroscopicliquid is-brought intoheat exchange relationship with the I compressedrefrigerant, under evaporative conditions for concentration ofthe-hygroscopic liquid and condensation of the refrigerant, anevaporative cooling tower includ-.

ing'a plurality of extended surface coils, means for causing a stream ofwater to flow,downwardly over said coils, means for flowing a'st ream ofair upwardly over said coils, means for passing condensed refrigerantthrougha portion of said coils, means for passing concentrated brinethrough another portion of said coils, and means for bringing waterwhich has passed over said coils into heat exchange relationshipwith theair being contacted with the hygroscopic liquid.

12, An air conditioning system comprising a compression-expansionrefrigerant cycleinclud ing heat transfer means for the transfer of heatfrom theconditioned area to the: refrigerant, a hygroscopic liquid cycleincluding means for'contactin'g air supplied to the conditi'oned'areawith the hygroscopic-liquid for removal of moisture from the air, heatexchange means whereby the hygroscopic liquid is brought intohatexchange relationship. with the compressed refrigerant under evaporativeconditions for concentration of the hygroscopic. liquid and condensationof the refrigerant, means for "subjecting a stream of water-tome'evaporative'cooling. effect of a current of air, and means'for bringingthe consaid cooling coils, over said extended surface and over theextended surface condensingycoils of the refrigerant circuit, means for,passing a stream of water under conditions of free evaporation over theextended, surface cooling coils of both the refrigerant circuit and thedehumidifying circuit, means for bringingsaidstream of water into heatcxchange relation with the exb tended contact surface of thedehumidifyingcirq densed refrigerant and, the concentrated hygroscopicliquid into heat exchange relationship with ,the'streamof water atpointswhere the temperature of the water is substantially the saine asthe temperature of the refrigerant and the hygroscopic liquid beingbrought into heat exchange relationship therewith.

